High molecular weight linked esterified propoxylated glycerins useful as gelling or thickening agents

ABSTRACT

Reduced calorie food compositions are prepared using linked esterified alkoxylated polyol fat substitutes comprised of polycarboxylate linking segments, polyol segments, and C 6  -C 24  monocarboxylic fatty acid-esterified oxyalkylene segments, and, optionally, oxyalkylene segments between the polycarboxylate linking segments and the polyol segments. The fat substitutes are obtainable by alkoxylating a polyol such as glycerin with an epoxide such as propylene oxide and esterifying the resulting alkoxylated polyol with both a polycarboxylic acid or an equivalent thereof and a C 6  -C 24  monocarboxylic fatty acid or an equivalent thereof, either simultaneously or sequentially.

This is a continuation, of application Ser. No. 08/166,323 filed on Dec.10, 1993, now U.S. Pat. No. 5,427,815.

FIELD OF THE INVENTION

This invention relates to reduced calorie fat substitutes which areesterified alkoxylated polyols containing polycarboxylate linkingsegments. These fat mimetics are obtainable by esterifying analkoxylated polyol such as propoxylated glycerin with at least one C₆-C₂₄ monocarboxylic acid entity such as a fatty acid and at least onepolycarboxylic acid entity such as azelaic acid or a dimer fatty acid.The linked esterified alkoxylated polyols are useful as fully functional, replacements for edible lipids in the preparation of food compositionshaving significantly decreased caloric content. The fat substitutescontain a minimal number of hydrolyzable ester bonds as compared toanalogous substances utilizing ester-bridged side chains.

BACKGROUND OF THE INVENTION

The consumption of high levels of triglyceride lipids has beenassociated with a number of health problems. Currently, obesity is oneof the more prevalent metabolic problems among the general population.This condition in many people is attributed to the ingestion of agreater number of calories than is actually needed to supply energy forthe maintenance and functioning of the body. Lipids are the mostconcentrated form of energy in the diet, with each gram of atriglyceride contributing about nine calories.

Maintaining a strict low fat diet, however, is difficult due to the factthat most people prefer the taste of "rich" foods, that is, foods thathave the satisfying mouthfeel associated with fats and oils. In orderfor a reduced calorie food composition to adequately replace aconventional foodstuff, the fat substitute used in its preparation mustmimic as closely as possible the organoleptic qualities of atriglyceride. The fat substitute must additionally have physicalproperties (viscosity, melting point, heat stability, thermalconductivity, etc.) resembling those of natural lipids since suchproperties often play a key role during preparation of a foodcomposition. For example, in deep fat frying the oil acts as a heattransfer medium so as to impart crispness to the food being fried. Atthe same time, the ideal fat substitute should be non-toxic and shouldnot cause any undesirable gastrointestinal side effects such as anal oilleakage, gas formation or diarrhea. This combination of attributes hasin practice been quite difficult to achieve; the need to developcompletely acceptable reduced calorie fat substitutes thus still exists.

U.S. Pat. No. 4,980,191 (Christensen) describes digestively hydrolyzablelow calorie edible oil substitutes. The substitutes are esterified formsof polymerized C₁₈ unsaturated fatty acids that have the property ofbeing at least partially hydrolyzed during digestion into simplealcohols and polybasic acids. Although the polybasic acids generatedduring digestion are higher in viscosity than the corresponding estersprior to hydrolysis, thus helping to avoid a laxative effect, these fatsubstitutes are not ideal since the alcohol portion does contributecalories to the diet. Moreover, the liberated alcohol may have otherundesirable effects. For example, where ethyl esters are employed, as inthe preferred embodiment of the described substitutes, the ethanolproduced will act as an intoxicant. Other types of esters, such asmethyl esters, may generate toxic alcohols when ingested.

U.S. Pat. No. 5,219,604 (Klemann et al.) teaches the use in fatsubstitutes of inter- and intramolecular ester bridges of the formula--O--CO----CH₂)_(n) --(CO--O-- where n is 1 to 8 formed by reactingdibasic acids with hydroxyl groups on the fatty side chains of fatcompounds. Such fat substitutes, through the incorporation of hydroxyacids, thus inherently contain multiple ester linkages capable of beinghydrolyzed upon ingestion. Where such hydrolysis takes place, theresulting hydrozylates are susceptible to further digestion; such fatsubstitutes may therefore have a higher level of available calories thanotherwise would be desirable. Moreover, hydroxy fatty acids have certaindeleterious physiological effects. The use of hydroxy fatty acids toprepare a fat substitute thus may not be desirable if digestion of thefat substitute will release such substances in the digestive tract.

U.S. Pat. No. 5,137,743 (Zaks et al.) describes the preparation oftexturized oils and oil-continuous emulsions by combining liquid oilswith minor amounts of certain high molecular weight polyester polymers.The polyester polymers include members of the class of polymersgenerally known as "alkyd" polymers, which are obtained by reaction of apolyhydric alcohol such as glycerol, a polybasic acid, and a fatty acidor oil. There is no suggestion, however, that the polyester polymers(which in the examples provided are in the form of powders) could beused by themselves at high levels as difficult to digest fatreplacements in the preparation of reduced calorie food products.

SUMMARY OF THE INVENTION

This invention furnishes a reduced calorie fat substitute which is alinked esterified alkoxylated polyol comprised of at least onepolycarboxylate linking segment, at least two polyol segments, and atleast one C₆ -C₂₄ monocarboxylic fatty acid-esterified oxyalkylenesegment attached to a polyol segment, wherein each polyol segment isconnected to a polycarboxylate linking segment either directly orthrough an oxyalkylene segment. Preferably, the polycarboxylate linkingsegment(s) has the general structure ##STR1## wherein X is an aliphaticmoiety comprised of from 1 to 10 carbon atoms and up to 2 carbon-carbondouble bonds or ##STR2## wherein w is 2 or 3 and A represents thehydrocarbyl portion of a dimerized or trimerized fatty acid, the polyolsegments have the general structure R--O)_(n) wherein R is a C₃ -C₁₂hydrocarbyl group and n is an integer of from 3 to 8, the C₆ -C₂₄monocarboxylic acid-esterified oxyalkylene segment(s) has the generalstructure ##STR3## wherein oxyalkylene is oxyethylene, oxypropylene, oroxybutylene, Z is an integer of from 1 to 10, and R¹ is a C₅ -C₂₃hydrocarbyl group, and the optionally present oxyalkylene segment hasthe general structure -(oxyalkylene¹)_(y) wherein oxyalkylene¹ isoxyethylene, oxypropylene, or oxybutylene and y is an integer of from 1to 10. It is also highly desirable that the linked esterifiedalkoxylated polyol contain from 2 to 4 polyol segments and have amolecular weight of from 750 to 6000. Preferably, the number of C₆ -C₂₄monocarboxylic fatty acid-esterified segments is at least equal to thenumber of polyol segments.

The present invention also provides a linked esterified alkoxylatedpolyol useful as a reduced calorie fat substitute obtainable byesterification of an alkoxylated polyol with at least one C₆ -C₂₄monocarboxylic acid entity and at least one polycarboxylic acid entity.In a particularly preferred embodiment, the linked esterifiedalkoxylated polyol is obtainable by alkoxylation of a polyol having from3 to 8 hydroxyl groups with from n to 10 n equivalents of a C₂ -C₆aliphatic epoxide, wherein n is equal to the number of hydroxyl groupson the polyol, to form an alkoxylated polyol and (b) esterification ofthe alkoxylated polyol with both (i) at least one C₆ -C₂₄ monocarboxylicacid entity and (ii) a polycarboxylic acid entity selected from dimer ortrimer fatty acid entities and dicarboxylic acid entities having thegeneral structure ##STR4## wherein X is is an aliphatic moiety comprisedof from 1 to 10 carbon atoms and up to 2 carbon-carbon double bonds andY is hydroxy, halide, or alkoxy, wherein the amount of C₆ -C₂₄monocarboxylic acid acid entity is from 1 to n-1 moles per mole ofpolyol and the amount of polycarboxylic acid entity is from 1/z to n-1/zmoles per mole of polyol, where z is equal to the number of carboxylatefunctionalities in the polycarboxylic acid entity.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 illustrates in schematic form an exemplary linked esterifiedalkoxylated polyol of this invention.

DETAILED DESCRIPTION OF THE INVENTION

The linked esterified alkoxylated polyol fat substitutes of thisinvention are organic compounds comprised of at least three types ofcovalently bonded moieties; namely, (1) polycarboxylate linkingsegments, (2) polyol segments, and (3) C₆ -C₂₄ monocarboxylic fattyacid-esterified oxyalkylene segments. These moieties are connected toeach other through either ether or ester bonds. Oxyalkylene segments notesterified with monocarboxylic fatty acid may optionally also bepresent. In a preferred embodiment, the total number of polycarboxylatelinking segments, unesterified oxyalkylene segments, and C₆ -C₂₄monocarboxylic fatty acid-esterified oxyalkylene segments attached toeach polyol segment is equal to the number of hydroxyl groups on thepolyol from which said polyol segment is derived. However, it is alsopossible for a portion of the hydroxyl groups on the polyol to remain asfree (unreacted) hydroxyl groups pendant to the polyol segment in thelinked esterified alkoxylated polyol. Preferably, no more than onehydroxyl group is pendant to the polyol segment.

The polycarboxylate linking segments function so as to link togethercertain polyol segments within the fat substitute, either directly orthrough oxyalkylene segments, and are characterized by the presence ofat least two carboxylate functionalities capable of forming ester bondsto said polyol or oxyalkylene segments. More than two carboxylatefunctionalities may also be present; di-, tri-, and tetracarboxylatelinking segments are thus possible, for example. While the identity ofthe remainder of the polycarboxylate linking segment is not critical, itis generally preferred that it be aliphatic in character and not containany aromatic, nitrogenous, or halogenated groups. Carbon-carbon doublebonds or alicyclic groups may advantageously be present, however.

In one particular preferred embodiment, the polycarboxylate linkingsegment corresponds to the general structure ##STR5## wherein X is analiphatic moiety comprised of from 1 to 10 carbon atoms and up to 2carbon-carbon double bonds. For example, X may be --CH₂)_(m) where m isan integer of from 1 to 10. Polycarboxylate linking segments of thistype thus may be derived from dicarboxylic acids or their functionalequivalents (halides, anhydrides, esters) such as, for example, malonic,succinic, glutaric, adipic, pimelic, suberic, azelaic, sebacic,undecanedioic, dodecanedioic, and brassylic acid and mixtures orcombinations thereof. Branched, substituted (includinghydroxy-substituted), or unsaturated di- and tri-carboxylic acidentities may also be utilized, including, without limitation,carboxystearic acid, polycarboxystearic acid, tricarballylic acid,aconitic acid, maleic acid, tartaric acid, citric acid, maleic acid,citraconic acid, cyclohexane dicarboxylic acid, ethyl malonic acid,methyl succinic acid, 2,2-dimethyl succinic acid, methyl glutaric acid,fumaric acid, methyl adipic acid, 2-ethyl-2-methyl succinic acid,diethyl malonic acid, tartaric acid, thapsic acid, dimethyl glutaricacid, cyclohexane diacetic acid, C₂₁ dicarboxylic acid (obtainable, forexample, by reacting linoleic acid with acrylic acid), and theirhalides, anhydrides, esters and the like and mixtures thereof.

In another desirable embodiment, the polycarboxylate linking segment isderived from a dimer fatty acid, a trimer fatty acid, or a mixture ofdimer and trimer fatty acids or their equivalents (halide, ester,anhydride). Such substances are well-known and are described, forexample, in Leonard, "Dimer Acids", Kirk-Othmer Encyclopedia of ChemicalTechnology, 3rd Ed., Vol. 7, pp. 768-782 (1979), Leonard, The DimerAcids, Humko Sheffield Chemical (1975), Johnson, "Dimerization andPolymerization", in E. H. Pryde, ed., Fatty Acids, American OilChemists' Society, pp. 343-352, (1979), and Pryde et al., "AliphaticDibasic Acids", in Condensation Monomers, Wiley-Interscience (1972).Especially preferred for use are the dimer and trimer fatty acids formedby the polymerization of C₁₈ unsaturated fatty acids such as oleic acid,linoleic acid, linolenic acid, elaidic acid and the like. The dimerfatty acid may have an acyclic, monocyclic, or bicyclic structure orcomprise a mixture of compounds having different such structures. Theuse of a dimer or trimer fatty acid entity furnishes a polycarboxylatelinking segment having the general structure ##STR6## wherein w is 2 (asin a dimer acid) or 3 (as in a trimer acid) and A is the hydrocarbylportion of a dimerized or trimerized fatty acid. Reference is made toFIG. 1 on page 348 of the Johnson publication referred to above, whereinexamples of dimer structures are illustrated.

The oxyalkylene segments which may optionally be present in the fatsubstitute are interspersed between the polyol segments and thepolycarboxylate linking segments, being connected to the former throughether bonds and to the latter through ester bonds. The oxyalkylenesegments are not directly attached to a fatty monocarboxylic acid acylgroup. Each oxyalkylene segment is comprised of one or morecarbon-carbon-oxygen sequences, i.e., ##STR7## wherein y is at least 1and preferably is not more than 10. An individual oxyalkylene segmentmay thus be monomeric or oligomeric in character and may be derived byring-opening of an epoxide (a three membered cyclic ether). Especiallypreferred for use are C₂ -C₁₀ aliphatic epoxides such as, for example,ethylene oxide, propylene oxide, 1,2-butene oxide, 2,3-butene oxide (cisand/or trans), isobutylene oxide, 1,2-pentene oxide, 2,3-pentene oxide,cyclopentene oxide, 1,2-hexene oxide, cyclohexene oxide, and the likeand mixtures thereof. In certain embodiments of this invention, the useof C₃ and higher 1,2-alkylene oxides such as propylene oxide and1,2-butene oxide is particularly desirable so as to create predominatelysecondary ester bonds between the terminus of the oxyalkylene segmentand the polycarboxylate linking segment. It may in certain applicationsbe advantageous to control the structure of the ester bonds such that atleast 95% of such bonds are secondary and less than 5% of such bonds areprimary. An oxyalkylene segment thus may have the general structure##STR8## wherein R is hydrogen or C₁ -C₆ alkyl (methyl, ethyl,cyclohexyl, and the like) and y is an integer of from 1 to 10. The valueof y may, of course, vary between individual oxyalkylene segments withinthe same linked esterified alkoxylated polyol. An oxyalkylene segmentmay advantageously be comprised of different types of ring-openedepoxide units (for example, both oxyethylene and oxypropylene units)which are present in either a random or block configuration.

The C₆ -C₂₄ monocarboxylic fatty acid-esterified oxyalkylene segmentsare attached to the polyol segments through ether bonds and arethemselves individually comprised of both an oxyalkylene segment and afatty acid acyl group. Said oxyalkylene segment may correspond instructure to the oxyalkylene segments described previously hereinabove(e.g., oxyethylene, polyoxyethylene, oxypropylene, polyoxypropylene,oxybutylene, polyoxybutylene, mixed polyoxyethylene/oxypropylene,preferably containing from 1 to 10 ring-opened epoxide units). The fattyacid acyl group, which is connected to the oxyalkylene segment of the C₆-C₂₄ monocarboxylic acid-esterified oxyalkylene segment by an esterbond, preferably has the general structure ##STR9## wherein R is a C₅-C₂₃ hydrocarbyl group (linear or branched; saturated, monounsaturated,or polyunsaturated). The fatty acid acyl group is desirably derived froma monocarboxylic fatty acid or the equivalent thereof (halide, ester,anhydride). Such fatty acids and their equivalents are readily availableat low cost from natural sources such as edible triglycerides. Specificillustrative fatty acids suitable for use include, but are not limitedto, eicosanoic (arachidic) acid, heneicosanoic acid, docosanoic(behenic) acid, elaidic acid, tricosanoic acid, tetracosanoic(lignoceric) acid, caprylic acid, pelargonic acid, capric acid, caproicacid, lauric acid, palmitic acid, stearic acid, oleic acid, cetoleicacid, myristic acid, palmitoleic acid, gadoleic acid, erucic acid,rincinoleic acid, linoleic acid, linolenic acid, myristoleic acid,eleostearic acid, arachidonic acid, or mixtures or hydrogenatedderivatives of these acids. The fatty acids may be derived syntheticallyor from natural sources such as triglyceride lipids. Mixtures of fattyacid entities, such as the mixtures of fatty acids typically obtained byhydrolysis (splitting) of a triglyceride such as corn oil or soybeanoil, may advantageously be used.

The properties and characteristics of the linked esterified alkoxylatedpolyol may be varied or controlled as desired by adjusting the relativeproportions of C₆ -C₂₄ monocarboxylic fatty acid-esterified oxyalkylenesegments to polycarboxylate linking segments. Decreasing the C₆ -C₂₄monocarboxylic fatty acid-esterified oxyalkylene segment:polycarboxylate segment molar ratio generally will increase themolecular weight of the linked esterified alkoxylated polyol, forexample. The precise ratio selected for use is not critical and may varywithin wide limits depending upon other factors such as, for example,the number of hydroxyl groups on the polyol and the number ofcarboxylate functionalities on the polycarboxylic acid entity. Where thepolyol has three hydroxyl groups and the polycarboxylic acid entity is adicarboxylic acid, for example, illustrative ratios which are suitablefor use include 4:1, 5:2, 6:3, and 7:4.

The linked esterified alkoxylated polyols of this invention contain aminimum of two polyol segments, but may also contain three, four, or aneven higher number of such segments. To limit viscosity, it willgenerally be desirable for the linked esterified alkoxylated polyol tocontain no more than four polyol segments. Each polyol segment willcorrespond to the generic formula R--O)_(n) and is derived from a polyolor a polyol equivalent wherein the polyol is a polyhydric alcoholcontaining three or more hydroxyl groups. R in the foregoing formulathus is an organic moiety such as a hydrocarbyl entity containing atleast three carbon atoms, hydrogen, and, optionally, other elements suchas oxygen or nitrogen; the polyol segments are connected to bothoxyalkylene segments and C₆ -C₂₄ monocarboxylic acid-esterifiedoxyalkylene segments through ether bonds. In preferred embodiments, thepolyol segment does not contain any hydrolyzable ester groups. Thenumber of hydroxyl groups on the polyol (n) is most suitably from 3 to8. The polyol (which preferably contains primary and/or secondaryhydroxyl groups) may be selected from C₃ -C₁₂ aliphatic triols (e.g.,glycerol, 1'2'4-butane triol, 2,3,4-pentane triol,2-ethyl-2-(hydroxymethyl)-1,3-propane triol (trimethylol propane),1,1,1-tris(hydroxymethyl)ethane, 1,2,6-trihydroxyhexane,1,2,3-heptanetriol, and the like), C₄ -C₁₂ aliphatic tetrols (eg.,erthyritol, sorbitan, pentaerythritol), C₅ -C₈ sugar alcohols [includingthose compounds corresponding to the formula HOCH₂ (CHOH)_(n) CH₂ OHwherein n is 3 to 6 such as xylitol, sorbitol, arabitol, mannitol, andthe like], monosaccharides (e.g., erythrose, threose, ribose, arabinose,xylose, lyxose, allose, altrose, glucose, mannose, gulose, idose,galactose, fructose, galactose, and the like), disaccharides (e.g.,sucrose, lactose, maltose) and alkyl glycosides (e.g., methylglycosides, ethyl glycosides, propyl glycosides, and other glycosidemolecules wherein the alkyl glycoside is an acetal formed by interactionof a C₁ -C₂₀ alcohol with a carbonyl group of a mono- or disaccharidesuch as glucose). Also suitable for use as the polyol arehydroxy-containing substances such as tetrahydrofuran oligomers, oxetaneoligomers, glycerol oligomers, and the like.

In a preferred embodiment, the polyol is glycerin so as to provide apolyol segment having the structure ##STR10## in the linked esterifiedalkoxylated polyol (i.e., R=C₃ H₅ and n=3 in the foregoing formula).Glycerin may be readily and economically obtained by hydrolyticsplitting of a natural triglyceride. The fatty acids obtained in such asplitting operation may also be utilized in the preparation of thelinked esterified alkoxylated polyol.

To better illustrate the interrelationships between the differentcomponents of the linked esterified alkoxylated polyol fat substitute ofthis invention, an example of such a substance is diagrammedschematically in FIG. 1. In this illustrative example, oxyalkylenesegment 1 is attached to polycarboxylate linking segment 2 by ester bond3. Oxyalkylene segment 4 is also attached to 2 by ester bond 5. Polyolsegment 6 is attached to 1 through ether bond 7, while polyol segment 8is similarly attached to 4 through ether bond 9. C₆ -C₂₄ monocarboxylicacid-esterified oxyalkylene segment 10, comprised of oxyalkylene segment11 and fatty acid acyl group 12 joined by ester bond 13, are attached to6 through ether bond 14. C₆ -C₂₄ monocarboxylic acid-esterifiedoxyalkylene segment 15, comprised of oxyalkylene segment 16 and fattyacid acyl group 17 joined by ester bond 18, are attached to 6 throughether bond 19. C₆ -C₂₄ monocarboxylic acid-esterified oxyalkylenesegment 20, comprised of oxyalkylene segment 21 and fatty acid acylgroup 22 joined by ester bond 23, are attached to 8 by ester bond 24. C₆-C₂₄ moncarboxylic acid-esterified oxyalkylene segment 25, comprised ofoxyalkylene segment 26 and fatty acid acyl group 27 joined by ester bond28, are attached to 8 through ether bond 29. Variations upon thisstructure will be readily apparent to the person of ordinary skill inthe art familiar with the teachings of the instant specification. Forexample, C₆ -C₂₄ monocarboxylic acid-esterified oxyalkylene segment 10could be replaced by another polycarboxylate linking segment which isitself connected to additional oxyalkylene, polyol, and C₆ -C₂₄monocarboxylic acid-esterified oxyalkylene segments. A polycarboxylatelinking segment could alternatively be connected to two oxyalkylenesegments, which in turn are both attached to the same polyol segment.One or both of oxyalkylene segments 1 and 4 could be omitted, resultingin direct attachment of the polyol segments to the polycarboxylatelinking segment.

The structure of a specific example of a linked esterified alkoxylatedpolyol within the class of fat substitutes embraced by the presentinvention may be represented as follows: ##STR11## wherein R¹ is (CH₂)₁₆CH₃, R² and R⁴ are (CH₂)₇ CH═CH --CH₂)₇ CH₃ and R³ is (CH₂)₂₀ CH₃.

To minimize direct absorption of the fat substitute through the walls ofthe gastrointestinal tract, it is highly advantageous for the molecularweight of the linked esterified alkoxylated polyol to be at least 750(more preferably, at least 900). To avoid undesirably high viscosities,the molecular weight generally should be no greater than 6000 andpreferably is 3000 or less. It will be particularly advantageous (wherethe linked esterified alkoxylated polyol is to be used to replace mostor all of the triglyceride portion of a food composition) to control themolecular weight, degree of cross-linking, and other structuralparameters such that the viscosity of the linked esterified alkoxylatedpolyol is less than 1000 cps (more preferably less than 500 cps; mostpreferably, less than 250 cps) as measured by Brookfield viscometer at100° F. (38° C.).

The higher molecular weight linked esterified alkolylated polyols, whileperhaps too viscous to be easily used alone as 100% replacements fortriglycerides in the fat component of a food composition, may beadvantageously blended with low viscosity digestible triglycerides ornon-linked esterified alkoxylated polyols (or other fat substitutes suchas sucrose polyester). Such linked esterified alkoxylated polyols maybeneficially act as gelling or thickening agents. For example, whencombined at the 0.5 to 25 weight % level with liquid unsaturatedtriglycerides, higher molecular weight linked esterified alkoxylatedpolyol in accordance with the invention may modify the viscosity ormelting properties of such triglycerides such that they closely resemblethose of solid or semi-solid fats containing high levels of saturatedfatty acids. Alternatively, the tendency of a liquid fat substitute suchas certain non-linked esterified alkoxylated polyols to exhibit anal oilleakage when consumed in large quantities may be effectively suppressedby incorporation of the linked esterified alkoxylated polyol. Reducedcalorie fat substitutes comprised of liquid triglycerides, liquidnon-linked esterified alkoxylated polyols, and higher molecular weightlinked esterified alkoxylated polyols may also provide certainadvantages (e.g. reduced anal oil leakage as compared to analogouscompositions not containing the linked esterified alkoxylated polyol).

The linked esterified alkoxylated polyol fat substitutes will deliverless than 9 Kcal/gram, preferably less than 5 Kcal/gram, and, in someembodiments, less than 3 Kcal/gram, upon being metabolized by the humanbody. Where a maximum reduction in the caloric content of a foodcomposition is desired, the linked esterified alkoxylated polyol may beselected such that it delivers essentially 0 Kcal/gram when consumed.

In preferred embodiments of the invention, the structures of the variousester bonds incorporated in the linked esterified alkoxylated polyol arecontrolled such that differential reactivity with respect to hydrolyticcleavage by digestive enzymes such as lipase is attained. This resultsnot only in a reduction in effective caloric value as compared to atriglyceride, but also the selective conversion of the fat substitute toa product or intermediate which is less oil-like in nature. The productof such a controlled digestive process may have decreasedhydrophobicity, and thus greater hydrophilicity, relative to the parentlinked esterified alkoxylated polyol. Such a product of a process ofcontrolled digestion will tend to have not only decreased oiliness, butmay also function as a emulsifier or surface active agent capable ofemulsifying any undigested fat substitute or oil-like digestive byproducts. Thus, the fat substitutes of this invention can be selectedsuch that they will resemble natural lipids (triglycerides) in taste andtexture when consumed, yet be less prone to exit the gastrointestinaltract as a persistent oil compared to certain substances taught as fatsubstitutes in the prior art.

One method by which the relative digestibility of the linked esterifiedalkoxylated polyol may be adjusted as may be desired for a particularapplication is to vary the extent of steric hinderance present at theester linkage. For example, bulky substitutents may be introduced on thecarbon atoms adjacent to the ester oxygen atom or the ester carbonylcarbon atom so as to block or interfere with the ability of the esterlinkage to closely associate with the active sites on the lipase enzymesresponsible for catalyzing ester hydrolysis.

The linked esterified alkoxylated polyols of this invention may beprepared by adaptation of conventional alkoxylation and esterificationtechniques. For example, a polyol may be reacted with the desired numberof equivalents of an epoxide in the presence of an appropriate catalyst(e.g., alkali metal) so as to ring-open the epoxide and to addoxyalkylene segments onto the hydroxyl groups of the polyol to form analkoxylated polyol. The alkoxylated polyol may then be reacted, eithersimultaneously or sequentially, with the desired combination andproportions of both a monocarboxylic fatty acid (or an anhydride, ester,or halide thereof) or mixture of monocarboxylic fatty acids and apolycarboxylic acid entity (free acid, anhydride, ester, or halide) ormixture of polycarboxylic acid entities so as to generate the linkedesterified alkoxylated polyol. Direct esterification (i.e., with freefatty acids, either self-catalyzed or with a suitable catalyst),transesterification (i.e., with methyl esters or the like, with orwithout catalyst), and interesterification methods may all be employed,together with other known procedures for forming ester bonds. Suchprocedures are described, for example, in Markley, "Esters andEsterification", in Fatty Acids, Markley, ed., Second Edition Part 2,Chapter IX, pp. 757-984 (1961). An alternative approach is tosimultaneously react epoxide, polyol, and a triglyceride (a fatty acidtriester of glycerin) in the presence of base or other suitable catalystto form a partially esterified alkoxylated polyol and to thereafterreact with the desired amount of polycarboxylic acid entity so as togenerate polycarboxylate linking segments.

To prepare linked esterified alkoxylated polyols wherein thepolycarboxylate linking segments are attached directly to polyolsegments without intervening oxyalkylene segments, alkoxylated polyolscontaining protective groups may be used. Such protective groups (e.g.,acetals, ketals, tertiary alkyl groups, tetrahydropyranyl groups,triphenylmethyl groups, benzyl groups) are placed on a portion of thehydroxyl groups of the polyol prior to alkoxylation, then removed priorto esterification. U.S. Pat. Nos. 5,118,448 and 5,135,683 describemethods for obtaining and reacting such alkoxylated polyols which may bereadily adapted for use in synthesizing linked esterified alkoxylatedpolyol fat substitutes of this type.

The relative molar proportions of C₆ -C₂₄ monocarboxylic acid entity andpolycarboxylic acid entity utilized may be varied within wide limits toattain the desired ratio of C₆ -C₂₄ monocarboxylic fatty acid-esterifiedoxyalkylene segments to polycarboxylate linking segments in the linkedesterified alkoxylated polyol. For example, it will typically bedesirable for the amount of monocarboxylic fatty acid reacted to be from1 to n-1 moles per mole of polyol and the amount of polycarboxylic acidto be from 1/z to n-1/z moles per mole of polyol where n is equal to thenumber of hydroxyl groups on the polyol and z is equal to the number ofcarboxylate functionalities in the polycarboxylic acid entity. In theembodiment of this invention wherein the polyol is a triol such asglycerin, the polycarboxylic acid entity is a dicarboxylic acid entity,and an average of from 2 to 4 polyol segments per molecule of the linkedesterified alkoxylated polyol is desired, the amount of the dicarboxylicacid entity reacted per mole of polyol should be from 0.5 to 0.75 moles.In another embodiment, substantially all of the available hydroxylgroups are esterified (either with monocarboxylic fatty acid orpolycarboxylic acid) such that the total of the number of moles ofmonocarboxylic, fatty acid plus z times the number of moles ofpolycarboxylic acid is equal to or nearly equal to n times the number ofmoles of polyol. Incompletely esterified substances will also besuitable for use, however, provided they exhibit physical andorganoleptic properties resembling natural fats and oils.

A reduced calorie fat substitute produced by the procedures describedhereinabove may be additionally purified or treated so as to render itmore suitable for use in food compositions using any of the techniquesknown in the art for refining natural vegetable or animal lipids. Suchtechniques include, but are not limited to, degumming, bleaching,filtration, deodorization, hydrogenation, dewaxing, and the like.Various additives such as stabilizers, anti-oxidants (e.g., tocopherols,hindered phenols such as BHT, hydroquinones such as TBHQ), vitamins(e.g., fat-soluble vitamins such as vitamin A, D, E, and K) and so forthcan also be incorporated into the linked esterified alkoxylated polyol.

It should be understood that by the nature of the reactions taking placeas described hereinabove during the preparation of the linked esterifiedalkoxylated polyols, the compositions obtained will generally bemixtures of individual compounds which have a range of molecular weightand which may contain different structural isomers. Also, depending uponthe synthetic procedure used, minor amounts of other materials such asnon-linked esterified alkoxylated polyols may be generated together withthe linked esterified alkoxylated polyols of this invention. The use ofsuch mixed reaction products as fat substitutes may be advantageousunder certain circumstances. For example, the presence of non-linkedesterified alkoxylated polyol may beneficially lower the viscosity,hardness or melting point of a linked esterified alkoxylated polyol.Non-linked esterified alkoxylated polyols of the type described in U.S.Pat. Nos. 4,861,613, 5,509,443, 5,077,073, and 4,980,191 and EuropeanPat. Publication No. 481,523 (incorporated herein by reference in theirentirety) may also be deliberately blended in any proportion (e.g., 1:99to 99:1) with the linked esterified alkoxylated polyols of thisinvention to provide reduced calorie fat substitutes.

The linked esterified alkoxylated polyols of this invention may be usedas partial or total (100%) replacements for conventional lipids in anyedible fat-containing food composition. The amount of the fat mimeticemployed is sufficient to effectively reduce the available calories ofthe food composition as compared to a food composition prepared using anequivalent amount (weight or volume) of a conventional fully digestibletriglyceride lipid alone. Preferably, at least about 10 percent (morepreferably, at least about 25 percent by weight) of the total fatcomponent of the food composition is comprised of the linked esterifiedalkoxylated polyol.

The triglyceride lipid admixed with the linked esterified propoxylatedglycerin composition may be any of the known edible fatty acidtriglycerides available from natural or synthetic sources. These ediblefatty acid triglycerides include, but are not limited to, fats and oilssuch as tallow, soybean oil, cottonseed oil, coconut oil, palm kerneloil, corn oil, fish oil, lard, butterfat, olive oil, palm oil, peanutoil, safflower seed oil, cocoa butter, sesame seed oil, rapeseed oil,sunflower seed oil, as well as fully or partially hydrogenatedderivatives and mixtures of these triglycerides. While the linkedesterified alkoxylated polyol composition may be combined in anyproportion with the triglyceride lipid, weight ratios of from 5:95 to95:5 are particularly advantageous. The triglyceride lipid may beselected so as to impart a desirable caloric content, flavor, aroma,mouth feel, thermal stability, viscosity, rheology (Newtonian ornon-Newtonian) or other property to the blend and to the final foodcomposition.

The physical, organoleptic, and physiological properties andcharacteristics of the linked esterified alkoxylated polyols of thisinvention may be controlled as desired by varying the identities andrelative proportions of the polyols, epoxides, polycarboxylic acids, andC₆ -C₂₄ monocarboxylic fatty acids incorporated therein. The compositionof the alkoxylated polyols may thus be readily altered so as to renderthe fat substitute completely liquid, completely solid, or partiallyliquid and partially solid at room temperature (i.e., the solid fatindex may range from 0 to 100%).

In certain embodiments of the invention (for example, where the linkedesterified alkoxylated polyol comprises at least 50% by weight of thefat component present in a food product), the linked esterifiedalkoxylated polyol preferably has a solid fat index as measured bydilatometry of from 0 to a maximum of 50 at body temperature (37° C.) toprovide a pleasant creamy or smooth (i.e., non-waxy) consistency andtexture in the food product.

The fat substitute of this invention can replace, in full or in part, atriglyceride lipid in a cooking oil, frying oil, salad oil, orshortening, for example. Additional uses include combining the linkedesterified alkoxylated polyol with other foodstuff ingredients to formfood compositions such as frozen desserts (e.g., sherbert, ice cream,frozen yogurt, milk shakes), baked goods (cakes, doughnuts, muffins,brownies, breads, pies, rolls, pastries, cookies, biscuits, crackers),nut butters (peanut butter), dairy products (margarine, sour cream,coffee lighteners, cheese, cheese spreads, flavored dips, filled cream,filled milk), mayonnaise, salad dressing, savory snacks (potato chips,corn chips, cheese puffs, pretzels), fried foods (fried poultry,fritters, fried pies, fried vegetables such french fried potatoes, friedfish), reformed and comminuted meats (lunch meats, sausage, hot dogs,hamburger), pet foods, meat and egg substitutes or extenders, whippedtoppings, gravies and other sauces, frostings, fillings, icings, cocoabutter replacements or blends, candies and confectioneries (especiallythose normally containing fatty ingredients such as chocolate or peanutbutter), soups, and dry baking mixes (for muffins, cakes, pancakes,waffles, brownies, and the like). Owing to the fat-like properties andstability of the linked esterified alkoxylated polyols, minimumreformulation of standard food compositions will generally be required.The viscosity, melting profile, yield point, hardness, thixotropic area,liquid/solid stability, solid fat index, rheology, plasticity, and otherphysical properties of the linked esterified alkoxylated polyol arepreferably selected such that they mimic as closely as possible theanalogous properties of the conventional triglyceride being replaced.

Illustrative ingredients (including both fatty food ingredients andnon-fat food ingredients) which may be used in combination with the fatmimetics of this invention include carbohydrates (flour, starches,sugars, celluloses), edible lipids (triglycerides), proteins (fromanimal or vegetable sources), vitamins (including, but not limited to,fat soluble vitamins such as vitamin A, vitamin D, vitamin E, andvitamin K), antioxidants, emulsifiers (including, but not limited to,the emulsifiers listed as approved for food use in the United StatesCode of Federal Regulations), thickeners, preservatives, colorants,flavors, fragrances, sugar substitutes (saccharin, aspartame, sucralose,cyclamates, and the like), other fat substitutes or fat mimetics (forexample, polyol polyesters such as sorbitol polyesters and sucrosepolyesters, non-linked esterified alkoxylated polyols such as esterifiedpropoxylated glycerin, or caprenin), bulking agents such aspolydextrose, dietary fibers, water, milk, spices, eggs, and the like.Oil-in-water or water-in-oil emulsions can be readily prepared bycombining water, the linked esterified alkoxylated polyol, and otheringredients such as emulsifiers. The linked esterified alkoxylatedpolyols of this invention are particularly suitable for the preparationof food compositions requiring exposure to elevated temperatures. Unlikeother proposed fat substitutes such as proteinacious macrocolloids orcertain polysaccharide-based substances requiring water to render themfat-like in texture, the fat mimetics of this invention are thermallystable and do not readily decompose or lose their fat-like propertieswhen heated. The fat mimetics thus may readily be utilized in deep fatfrying applications to prepare fried foods such as savory snacks, friedchicken, fried fish, french fries, and the like since they will functionas effective heat transfer media (that is, they will transmit heatrapidly and uniformly to the food being fried and also providecrisping).

From the foregoing description, one skilled in the art can readilyascertain the essential characteristics of this invention and, withoutdeparting from the spirit and scope thereof, make various changes andmodifications to the invention to adapt it to various usages,conditions, and embodiments.

The following examples further illustrate the compositions of thisinvention, but are not limitative of the invention in any mannerwhatsoever.

EXAMPLE 1

This example demonstrates the preparation of a linked esterifiedalkoxylated polyol in accordance with the invention. A propoxylatedglycerin (324.4 parts by weight) prepared by reacting 4 equivalents ofpropylene oxide with 1 equivalent of glycerin in the presence of apotassium catalyst is treated with magnesium silicate to remove residualcatalyst, combined with stearic acid (569.0 parts) and tin (II) chloride(5.4 parts), then heated under vacuum (10 torr) at 150° C. with nitrogensparging until at least 95% conversion of the stearic acid has occurred.Adipic acid (73.1 parts) is then added and heating continued at a vacuumof 100 mm until at least 95% conversion of the hydroxyl groups of theinitial propoxylated glycerin has been attained. Any unreacted adipicacid taken overhead is recycled. Catalyst is removed by washing thereaction product five times with an equal volume of water, heating thewashed product with magnesium silicate (5% by weight) for 2 hours at 90°C., and filtering. The filtered product is steam stripped under 10 mm Hgpressure until the residual acidity is less than 1 mg KOH/gram. Thepurified linked esterified alkoxylated polyol thereby obtained is usefulas a fat substitute in the preparation of reduced calorie food products.

EXAMPLE 2

The procedure of Example 1 is repeated using oleic acid (564.9 parts)instead of stearic acid and brassylic acid (122.2 parts) instead ofadipic acid. The oleic acid and brassylic acid are reactedsimultaneously with the propoxylated glycerin at a temperature of 125°C. and a vacuum of 10 mm Hg until greater than 95% esterification of thehydroxy groups of the propoxylated glycerin is achieved. The expectedproduct is a linked esterified alkoxylated polyol suitable for use inreducing the caloric content of a fat component-containing food product.

EXAMPLES 3-11

These examples demonstrate the preparation of linked esterifiedalkoxylated polyol fat substitutes within the scope of this inventionusing different alkoxylated polyols, C₆ -C₂₄ monocarboxylic acidentities, and polycarboxylic acid entities in varying proportions. Thereactants listed in Table I are reacted using conditions similar tothose described in Example 1, except that in Examples 3-5 the potassiumcatalyst used to prepare the alkoxylated polyol is not removed prior tothe esterification steps. The desired esterification is catalyzed by theresidual potassium catalyst in the alkoxylated polyol; the tin (II)chloride is omitted and the reactants heated at 200° C. and a pressureof 10 mm Hg (to remove the methanol co-product generated duringtransesterification) until at least 95% conversion of both the C₆ -C₂₄monocarboxylic acid and the hydroxyl groups of the initial alkoxylatedpolyol is achieved. Following purification, a linked esterifiedalkoxylated polyol useful as a reduced calorie replacement fordigestible triglycerides in food compositions is expected to be obtainedin each example.

                                      TABLE I                                     __________________________________________________________________________                                                      Molar Ratio                 Example            Epoxide:Polyol                                                                        C.sub.6 -C.sub.24 Monocarboxylic                                                          Polycarboxylic Acid                                                                      Alkoxylated                                                                   Polyol:Fatty                No.  Epoxide                                                                              Polyol molar ratio                                                                           Acid Entity Entity     Acid:Polycarboxylic         __________________________________________________________________________                                                      Acid                        3    ethylene                                                                             trimethylol                                                                             6:1  soybean oil fatty acid                                                                    e               2:3.22:1                    oxide  propane        methyl esters                                      4    1,2-butene                                                                           1,2,6-hexane                                                                           10:1  partially hydrogenated                                                                    f             1.3:1.91:1                    oxide  triol          soybean oil fatty acid                                                        methyl esters (iodine                                                         value = 30)                                        5    a      diglycerol                                                                             12:1  fully hydrogenated high                                                                   g               2:5.98:1                                          erucic rapeseed oil fatty                                                     acid methyl esters                                 6    b      penta-    8:1  corn oil fatty acids                                                                      pimelic acid    3:8:2                              erythritol                                                        7    propylene                                                                            sucrose   8:1.sup.d                                                                          cottonseed oil fatty acids                                                                azelaic acid    2:14:1                      oxide                                                                    8    c      sorbitol 18.1  beef tallow fatty acids                                                                   sebacic acid    4:18:3                 9    ethyl glycidyl                                                                       methyl   10:1  coconut oil fatty acids                                                                   dodecanedioic acid                                                                            2:3:1                       ether  glucoside                                                         10   1,2-hexene                                                                           2,3,4,5-hexane                                                                          5:1  2:1 (by weight) blend of                                                                  C.sub.21 dicarboxylic                                                                         4:10:3                      oxide  tetrol         fully hydrogenated high                                                                   (from linoleic acid)                                              erucic rapeseed oil fatty                                                     acids and peanut oil fatty                                                    acids                                              11   propylene                                                                            xylitol  20:1  canola oil fatty acids                                                                    carboxystearic acid                                                                           2:8:1                       oxide                             (C.sub.19 dicarboxylic                 __________________________________________________________________________                                           acid)                                   a. mixture of ethylene oxide and propylene oxide (equimolar amounts)          b. mixture of propylene oxide and 1,2butene oxide (molar ratio 3:1)           c. ethylene oxide (528 parts) reacted first with the sorbitol (182 parts)     followed by propylene oxide (348 parts)                                       d. prepared in accordance with the procedures described in U.S. Pat. No.      2,908,681 (Anderson et al.)                                                   e. methyl esters of polymerized C.sub.18 fatty acids comprised of 2%          monobasic acid, 18% dibasic acid (dimer), and 80% tribasic acid (trimer),     prepared in accordance with U.S. Pat. No. 4,980,191 (Christensen)             f. methyl esters of polymerized C.sub.18 fatty acids comprised of 3%          monobasic acid, 35% dibasic acid (dimer), and 62% tribasic acid (trimer)      ester, prepared in accordance with U.S. Pat. No. 4,980,191 (Christensen)      g. methyl ester of polymerized C.sub.18 fatty acids comprised of 1%           monobasic acid, 96% dibasic acid (dimer), and 3% tribasic acid (trimer)       esters, prepared in accordance with U.S. Pat. No. 4,980,191 (Christensen)

EXAMPLE 12

This example demonstrates the utility of the linked esterifiedalkoxylated polyols of this invention in the formulation of foodproducts having significantly reduced caloric content as compared toanalogous products prepared using natural triglycerides (i.e., vegetableoils) exclusively.

A vanilla-flavored frozen dessert is prepared by mixing 10X sugar (15.0parts by weight), non-fat dry milk (3.9 parts), and salt (0.4 parts)into water (39.0 parts) for 3 minutes. The linked esterified alkoxylatedpolyol of Example 1 (28.4 parts) is then added in liquid form and theresulting mixture cooked to 200° F. while stirring. The mixture iscooled to 160° F. Sugared egg yolks (12.5 parts) and vanilla extract(0.8 parts) are added and mixed well. The resulting product is cooledand then frozen to yield the vanilla-flavored frozen dessert.

We claim:
 1. A composition useful as a reduced calorie fat substitutecomprising:(a) a liquid non-linked esterified propoxylated glycerin; and(b) a linked esterified propoxylated glycerin comprised of:(i) at leasttwo polycarbonyl linking segments; (ii) at least three glycerylsegments; and (iii) at least one C₆ -C₂₄ monocarboxylic fatty-acidesterified oxypropylene segment attached to a glyceryl segment; whereineach glyceryl segment is connected to a polycarbonyl linking segmenteither directly or through an oxypropylene segment and the linkedesterified propoxylated glycerin has a molecular weight greater than6000.
 2. The composition of claim 1 wherein the proportion of liquidnon-linked esterified propoxylated glycerin to linked esterifiedpropoxylated glycerin is from 1:99 to 99:1.
 3. The composition of claim1 additionally comprising a liquid triglyceride.
 4. The composition ofclaim 1 wherein the linked esterified propoxylated glycerin has aviscosity of greater than 1000 cps as measured by Brookfield viscometerat 100° F.
 5. The composition of claim 1 wherein the polycarbonyllinking segments have the general structure ##STR12## wherein X is analiphatic moiety comprised of 1 to 10 carbon atoms and up to 2carbon-carbon double bonds.
 6. The composition of claim 1 wherein thepolycarbonyl linking segments have the general structure ##STR13##wherein w is 2 or 3 and A represents the hydrocarbyl portion of adimerized or trimerized fatty acid.
 7. The composition of claim 1wherein the C₆ -C₂₄ monocarboxylic fatty acid-esterified oxypropylenesegment has the general structure ##STR14## wherein z is an integer offrom 1 to 10 and R is a C₅ -C₂₃ hydrocarbyl group.
 8. A method ofsuppressing the tendency of a liquid non-linked esterified propoxylatedglycerin fat substitute to exhibit anal oil leakage when consumedcomprising incorporating into said liquid non-linked esterifiedpropoxylated glycerin fat substitute a linked esterified propoxylatedglycerin comprised of:(a) at least two polycarbonyl linking segments;(b) at least three glyceryl segments; and (c) at least one C₆ -C₂₄monocarboxylic fatty acid esterified oxypropylene segment attached to aglyceryl segment, wherein each glyceryl segment is connected to apolycarbonyl linking segment either directly or through an oxypropylenesegment and the linked esterified propoxylated glycerin has a molecularweight greater than 6000.